Manipulation of playback device response using an acoustic filter

ABSTRACT

An acoustic filter includes holes and is configured to receive sound waves generated by an audio driver of a playback device. The sound waves comprise sound waves of a first frequency that radiate according to a first radiation pattern and sound waves of a second frequency that radiate according to a second radiation pattern that is less directed along an axis of the audio driver than the first radiation pattern. The second frequency is lower than the first frequency. The acoustic filter is configured to attenuate the sound waves of the first frequency so that the attenuated sound waves of the first frequency are emitted from the acoustic filter according to an effective radiation pattern that is less directed along the axis of the audio driver than the first radiation pattern and pass the sound waves of the second frequency in substantial accordance with the second radiation pattern.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 120 to, and is acontinuation of, U.S. patent application Ser. No. 14/831,903, filed onAug. 21, 2015, entitled “Manipulation of Playback Device Response Usingan Acoustic Filter,” which is incorporated herein by reference in itsentirety.

FIELD OF THE DISCLOSURE

The disclosure is related to consumer goods and, more particularly, tomethods, systems, products, features, services, and other elementsdirected to media playback or some aspect thereof.

BACKGROUND

Options for accessing and listening to digital audio in an out-loudsetting were limited until in 2003, when SONOS, Inc. filed for one ofits first patent applications, entitled “Method for Synchronizing AudioPlayback between Multiple Networked Devices,” and began offering a mediaplayback system for sale in 2005. The Sonos Wireless HiFi System enablespeople to experience music from many sources via one or more networkedplayback devices. Through a software control application installed on asmartphone, tablet, or computer, one can play what he or she wants inany room that has a networked playback device. Additionally, using thecontroller, for example, different songs can be streamed to each roomwith a playback device, rooms can be grouped together for synchronousplayback, or the same song can be heard in all rooms synchronously.

Given the ever growing interest in digital media, there continues to bea need to develop consumer-accessible technologies to further enhancethe listening experience.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, aspects, and advantages of the presently disclosed technologymay be better understood with regard to the following description,appended claims, and accompanying drawings where:

FIG. 1 shows an example media playback system configuration in whichcertain embodiments may be practiced;

FIG. 2 shows a functional block diagram of an example playback device;

FIG. 3 shows a functional block diagram of an example control device;

FIG. 4 shows an example controller interface;

FIG. 5 shows an example playback device with an acoustic filter;

FIG. 6 shows an example acoustic filter;

FIG. 7A shows example radiation patterns of an audio driver;

FIG. 7B shows an example acoustic filter and further example radiationpatterns of an audio driver;

FIG. 7C shows an example acoustic filter and yet further exampleradiation patterns of an audio driver;

FIG. 7D shows an example acoustic filter and additional exampleradiation patterns of an audio driver;

FIG. 8A shows experimental data representing a measured radiationpattern exhibited by a playback device; and

FIG. 8B shows experimental data representing a measured radiationpattern exhibited by a playback device configured with an acousticfilter.

The drawings are for the purpose of illustrating example embodiments,but it is understood that the inventions are not limited to thearrangements and instrumentality shown in the drawings.

DETAILED DESCRIPTION I. Overview

An audio playback device typically includes at least one audio driverthat generates sound waves according to various radiation patterns. Sucha radiation pattern may define directionally varying amplitudes of soundwaves produced by the corresponding audio driver (i) at a given audiofrequency (or range of audio frequencies), (ii) at a given radius fromthe audio driver, (iii) for a given amplitude of input signal. Aradiation pattern corresponding to an audio driver may be dependent onthe audio driver's construction, structure, geometry, materials, and/ororientation and position within an enclosure of the playback device, forexample. Generally, radiation patterns corresponding to low audiofrequencies are more omnidirectional than radiation patternscorresponding to high audio frequencies. For example, a tweeter of aplayback device may reproduce high audio frequencies (e.g., 12-16 kHz)according to a first radiation pattern that is defined by (i) a maximummagnitude along an axis of the tweeter and (ii) decreased magnitudes atdirections that are off-axis. The tweeter may reproduce low audiofrequencies (e.g., 6-10 kHz) according to a second radiation patternthat is defined by a relatively constant magnitude across a range ofmany directions. (It should be noted that the terms “low frequency” and“high frequency” may be used herein for purposes of describing and/orcomparing various ranges of audio frequencies, but such description isnot meant to be limiting in any way.)

In some applications, it may be useful to compensate for directionalvariances between a first radiation pattern corresponding to highfrequencies and a second radiation pattern corresponding to lowfrequencies. For instance, a listener located on the axis of the tweetermay perceive a relative loudness between the low frequencies and highfrequencies reproduced by the tweeter as a “true” representation of thesource audio content being played by the playback device. However, alistener located off the axis of the tweeter may perceive a distortedlyincreased loudness of the low frequencies relative to the loudness ofthe high frequencies when compared to what the listener located on theaxis of the tweeter perceives.

To help alleviate this problem, the first radiation pattern of thetweeter corresponding to high frequencies can be “reshaped” by placingan acoustic filter in front of the tweeter. (In other examples, anacoustic filter may be used to reshape a radiation pattern correspondingto an audio driver other than a tweeter.) Such an acoustic filter mayinclude an array of holes configured to receive high frequency soundwaves emitted by the tweeter over a given range of directions thatincludes the axis of the tweeter. The acoustic filter may attenuate thehigh frequency sound waves emitted over the given range of directions asthe high frequency sound waves compress the air within the holes. Theacoustic filter may pass low frequency sound waves emitted by thetweeter over the given range of directions without substantiallyaltering the amplitude of the low frequency sound waves. That is, theacoustic filter may pass the low frequency sound waves in substantialaccordance with the second radiation pattern. The acoustic filter may besized so that sound waves (of any frequency) emitted along directionsoutside the given range of directions will bypass the acoustic filterand not be substantially attenuated by the acoustic filter. This mayresult in an effective radiation pattern for the high frequenciesemitted by the tweeter that, when compared to the first radiationpattern, is less directed along the axis of the tweeter and has adistortedly reduced maximum magnitude along the axis of the tweeter. Tofurther compensate, the playback device may amplify high frequenciesreproduced by the tweeter to provide an effective radiation pattern forthe high frequencies that resembles the less direction-dependent secondradiation pattern of the low frequencies in both magnitude and shapeacross a relatively large range of directions. These techniques mayyield a better listening experience for listeners located at a varietyof locations.

Accordingly, some examples described herein include, among other things,an acoustic filter that is configured to be included as a component of aplayback device. In operation, the acoustic filter may receive soundwaves of a first frequency (or range of frequencies) emitted from anaudio driver of the playback device and reshape the radiation pattern ofthe sound waves of the first frequency to be less directed along an axisof the audio driver. The acoustic filter may also receive sound waves ofa second frequency (or range of frequencies) emitted from the audiodriver and pass the sound waves of the second frequency withoutsubstantial alteration. Other aspects of the examples will be madeapparent in the remainder of the description herein.

In one aspect, an acoustic filter includes holes and is configured toreceive sound waves generated by an audio driver of a playback device.The sound waves include (i) sound waves of a first frequency thatradiate according to a first radiation pattern and (ii) sound waves of asecond frequency that radiate according to a second radiation patternthat is less directed along an axis of the audio driver than the firstradiation pattern. The second frequency is lower than the firstfrequency. The acoustic filter is further configured to attenuate thesound waves of the first frequency so that the attenuated sound waves ofthe first frequency are emitted from the acoustic filter according to aneffective radiation pattern that is less directed along the axis of theaudio driver than the first radiation pattern. The acoustic filter isfurther configured to pass the sound waves of the second frequency insubstantial accordance with the second radiation pattern.

In another aspect, a playback device includes an audio driver configuredto generate (i) sound waves of a first frequency that radiate accordingto a first radiation pattern and (ii) sound waves of a second frequencythat radiate according to a second radiation pattern that is lessdirected along an axis of the audio driver than the first radiationpattern. The second frequency is lower than the first frequency. Theplayback device further includes an acoustic filter that includes holesthat are configured to receive the sound waves of the first frequencyand the sound waves of the second frequency. The holes are furtherconfigured to attenuate the sound waves of the first frequency so thatthe attenuated sound waves of the first frequency are emitted from theacoustic filter according to an effective radiation pattern that is lessdirected along the axis of the audio driver than the first radiationpattern. The holes are further configured to pass the sound waves of thesecond frequency in substantial accordance with the second radiationpattern.

It will be understood by one of ordinary skill in the art that thisdisclosure includes numerous other embodiments. While some examplesdescribed herein may refer to functions performed by given actors suchas “users” and/or other entities, it should be understood that this isfor purposes of explanation only. The claims should not be interpretedto require action by any such example actor unless explicitly requiredby the language of the claims themselves.

When the terms “substantially” or “about” are used herein, it is meantthat the recited characteristic, parameter, or value need not beachieved exactly, but that deviations or variations, including forexample, tolerances, measurement error, measurement accuracy limitationsand other factors known to those of skill in the art, may occur inamounts that do not preclude the effect the characteristic was intendedto provide.

II. Example Operating Environment

FIG. 1 shows an example configuration of a media playback system 100 inwhich one or more embodiments disclosed herein may be practiced orimplemented. The media playback system 100 as shown is associated withan example home environment having several rooms and spaces, such as forexample, a master bedroom, an office, a dining room, and a living room.As shown in the example of FIG. 1, the media playback system 100includes playback devices 102, 104, 106, 108, 110, 112, 114, 116, 118,120, 122, and 124, control devices 126 and 128, and a wired or wirelessnetwork router 130.

Further discussions relating to the different components of the examplemedia playback system 100 and how the different components may interactto provide a user with a media experience may be found in the followingsections. While discussions herein may generally refer to the examplemedia playback system 100, technologies described herein are not limitedto applications within, among other things, the home environment asshown in FIG. 1. For instance, the technologies described herein may beuseful in environments where multi-zone audio may be desired, such as,for example, a commercial setting like a restaurant, mall or airport, avehicle like a sports utility vehicle (SUV), bus or car, a ship or boat,an airplane, and so on.

a. Example Playback Devices

FIG. 2 shows a functional block diagram of an example playback device200 that may be configured to be one or more of the playback devices102-124 of the media playback system 100 of FIG. 1. The playback device200 may include a processor 202, software components 204, memory 206,audio processing components 208, audio amplifier(s) 210, speaker(s) 212,and a network interface 214 including wireless interface(s) 216 andwired interface(s) 218. In one case, the playback device 200 might notinclude the speaker(s) 212, but rather a speaker interface forconnecting the playback device 200 to external speakers. In anothercase, the playback device 200 may include neither the speaker(s) 212 northe audio amplifier(s) 210, but rather an audio interface for connectingthe playback device 200 to an external audio amplifier or audio-visualreceiver.

In one example, the processor 202 may be a clock-driven computingcomponent configured to process input data according to instructionsstored in the memory 206. The memory 206 may be a tangiblecomputer-readable medium configured to store instructions executable bythe processor 202. For instance, the memory 206 may be data storage thatcan be loaded with one or more of the software components 204 executableby the processor 202 to achieve certain functions. In one example, thefunctions may involve the playback device 200 retrieving audio data froman audio source or another playback device. In another example, thefunctions may involve the playback device 200 sending audio data toanother device or playback device on a network. In yet another example,the functions may involve pairing of the playback device 200 with one ormore playback devices to create a multi-channel audio environment.

Certain functions may involve the playback device 200 synchronizingplayback of audio content with one or more other playback devices.During synchronous playback, a listener will preferably not be able toperceive time-delay differences between playback of the audio content bythe playback device 200 and the one or more other playback devices. U.S.Pat. No. 8,234,395 entitled, “System and method for synchronizingoperations among a plurality of independently clocked digital dataprocessing devices,” which is hereby incorporated by reference, providesin more detail some examples for audio playback synchronization amongplayback devices.

The memory 206 may further be configured to store data associated withthe playback device 200, such as one or more zones and/or zone groupsthe playback device 200 is a part of, audio sources accessible by theplayback device 200, or a playback queue that the playback device 200(or some other playback device) may be associated with. The data may bestored as one or more state variables that are periodically updated andused to describe the state of the playback device 200. The memory 206may also include the data associated with the state of the other devicesof the media system, and shared from time to time among the devices sothat one or more of the devices have the most recent data associatedwith the system. Other embodiments are also possible.

The audio processing components 208 may include one or moredigital-to-analog converters (DAC), an audio preprocessing component, anaudio enhancement component or a digital signal processor (DSP), and soon. In one embodiment, one or more of the audio processing components208 may be a subcomponent of the processor 202. In one example, audiocontent may be processed and/or intentionally altered by the audioprocessing components 208 to produce audio signals. The produced audiosignals may then be provided to the audio amplifier(s) 210 foramplification and playback through speaker(s) 212. Particularly, theaudio amplifier(s) 210 may include devices configured to amplify audiosignals to a level for driving one or more of the speakers 212. Thespeaker(s) 212 may include an individual transducer (e.g., a “driver”)or a complete speaker system involving an enclosure with one or moredrivers. A particular driver of the speaker(s) 212 may include, forexample, a subwoofer (e.g., for low frequencies), a mid-range driver(e.g., for middle frequencies), and/or a tweeter (e.g., for highfrequencies). In some cases, each transducer in the one or more speakers212 may be driven by an individual corresponding audio amplifier of theaudio amplifier(s) 210. In addition to producing analog signals forplayback by the playback device 200, the audio processing components 208may be configured to process audio content to be sent to one or moreother playback devices for playback.

Audio content to be processed and/or played back by the playback device200 may be received from an external source, such as via an audioline-in input connection (e.g., an auto-detecting 3.5 mm audio line-inconnection) or the network interface 214.

The microphone(s) 220 may include an audio sensor configured to convertdetected sounds into electrical signals. The electrical signal may beprocessed by the audio processing components 208 and/or the processor202. The microphone(s) 220 may be positioned in one or more orientationsat one or more locations on the playback device 200. The microphone(s)220 may be configured to detect sound within one or more frequencyranges. In one case, one or more of the microphone(s) 220 may beconfigured to detect sound within a frequency range of audio that theplayback device 200 is capable or rendering. In another case, one ormore of the microphone(s) 220 may be configured to detect sound within afrequency range audible to humans. Other examples are also possible.

The network interface 214 may be configured to facilitate a data flowbetween the playback device 200 and one or more other devices on a datanetwork. As such, the playback device 200 may be configured to receiveaudio content over the data network from one or more other playbackdevices in communication with the playback device 200, network deviceswithin a local area network, or audio content sources over a wide areanetwork such as the Internet. In one example, the audio content andother signals transmitted and received by the playback device 200 may betransmitted in the form of digital packet data containing an InternetProtocol (IP)-based source address and IP-based destination addresses.In such a case, the network interface 214 may be configured to parse thedigital packet data such that the data destined for the playback device200 is properly received and processed by the playback device 200.

As shown, the network interface 214 may include wireless interface(s)216 and wired interface(s) 218. The wireless interface(s) 216 mayprovide network interface functions for the playback device 200 towirelessly communicate with other devices (e.g., other playbackdevice(s), speaker(s), receiver(s), network device(s), control device(s)within a data network the playback device 200 is associated with) inaccordance with a communication protocol (e.g., any wireless standardincluding IEEE 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, 802.15, 4Gmobile communication standard, and so on). The wired interface(s) 218may provide network interface functions for the playback device 200 tocommunicate over a wired connection with other devices in accordancewith a communication protocol (e.g., IEEE 802.3). While the networkinterface 214 shown in FIG. 2 includes both wireless interface(s) 216and wired interface(s) 218, the network interface 214 may in someembodiments include only wireless interface(s) or only wiredinterface(s).

In one example, the playback device 200 and one other playback devicemay be paired to play two separate audio components of audio content.For instance, playback device 200 may be configured to play a leftchannel audio component, while the other playback device may beconfigured to play a right channel audio component, thereby producing orenhancing a stereo effect of the audio content. The paired playbackdevices (also referred to as “bonded playback devices”) may further playaudio content in synchrony with other playback devices.

In another example, the playback device 200 may be sonicallyconsolidated with one or more other playback devices to form a single,consolidated playback device. A consolidated playback device may beconfigured to process and reproduce sound differently than anunconsolidated playback device or playback devices that are paired,because a consolidated playback device may have additional speakerdrivers through which audio content may be rendered. For instance, ifthe playback device 200 is a playback device designed to render lowfrequency range audio content (i.e. a subwoofer), the playback device200 may be consolidated with a playback device designed to render fullfrequency range audio content. In such a case, the full frequency rangeplayback device, when consolidated with the low frequency playbackdevice 200, may be configured to render only the mid and high frequencycomponents of audio content, while the low frequency range playbackdevice 200 renders the low frequency component of the audio content. Theconsolidated playback device may further be paired with a singleplayback device or yet another consolidated playback device.

By way of illustration, SONOS, Inc. presently offers (or has offered)for sale certain playback devices including a “PLAY:1,” “PLAY:3,”“PLAY:5,” “PLAYBAR,” “CONNECT:AMP,” “CONNECT,” and “SUB.” Any otherpast, present, and/or future playback devices may additionally oralternatively be used to implement the playback devices of exampleembodiments disclosed herein. Additionally, it is understood that aplayback device is not limited to the example illustrated in FIG. 2 orto the SONOS product offerings. For example, a playback device mayinclude a wired or wireless headphone. In another example, a playbackdevice may include or interact with a docking station for personalmobile media playback devices. In yet another example, a playback devicemay be integral to another device or component such as a television, alighting fixture, or some other device for indoor or outdoor use.

b. Example Playback Zone Configurations

Referring back to the media playback system 100 of FIG. 1, theenvironment may have one or more playback zones, each with one or moreplayback devices. The media playback system 100 may be established withone or more playback zones, after which one or more zones may be added,or removed to arrive at the example configuration shown in FIG. 1. Eachzone may be given a name according to a different room or space such asan office, bathroom, master bedroom, bedroom, kitchen, dining room,living room, and/or balcony. In one case, a single playback zone mayinclude multiple rooms or spaces. In another case, a single room orspace may include multiple playback zones.

As shown in FIG. 1, the balcony, dining room, kitchen, bathroom, office,and bedroom zones each have one playback device, while the living roomand master bedroom zones each have multiple playback devices. In theliving room zone, playback devices 104, 106, 108, and 110 may beconfigured to play audio content in synchrony as individual playbackdevices, as one or more bonded playback devices, as one or moreconsolidated playback devices, or any combination thereof. Similarly, inthe case of the master bedroom, playback devices 122 and 124 may beconfigured to play audio content in synchrony as individual playbackdevices, as a bonded playback device, or as a consolidated playbackdevice.

In one example, one or more playback zones in the environment of FIG. 1may each be playing different audio content. For instance, the user maybe grilling in the balcony zone and listening to hip hop music beingplayed by the playback device 102 while another user may be preparingfood in the kitchen zone and listening to classical music being playedby the playback device 114. In another example, a playback zone may playthe same audio content in synchrony with another playback zone. Forinstance, the user may be in the office zone where the playback device118 is playing the same rock music that is being played by playbackdevice 102 in the balcony zone. In such a case, playback devices 102 and118 may be playing the rock music in synchrony such that the user mayseamlessly (or at least substantially seamlessly) enjoy the audiocontent that is being played out-loud while moving between differentplayback zones. Synchronization among playback zones may be achieved ina manner similar to that of synchronization among playback devices, asdescribed in previously referenced U.S. Pat. No. 8,234,395.

As suggested above, the zone configurations of the media playback system100 may be dynamically modified, and in some embodiments, the mediaplayback system 100 supports numerous configurations. For instance, if auser physically moves one or more playback devices to or from a zone,the media playback system 100 may be reconfigured to accommodate thechange(s). For instance, if the user physically moves the playbackdevice 102 from the balcony zone to the office zone, the office zone maynow include both the playback device 118 and the playback device 102.The playback device 102 may be paired or grouped with the office zoneand/or renamed if so desired via a control device such as the controldevices 126 and 128. On the other hand, if the one or more playbackdevices are moved to a particular area in the home environment that isnot already a playback zone, a new playback zone may be created for theparticular area.

Further, different playback zones of the media playback system 100 maybe dynamically combined into zone groups or split up into individualplayback zones. For instance, the dining room zone and the kitchen zone114 may be combined into a zone group for a dinner party such thatplayback devices 112 and 114 may render audio content in synchrony. Onthe other hand, the living room zone may be split into a television zoneincluding playback device 104, and a listening zone including playbackdevices 106, 108, and 110, if the user wishes to listen to music in theliving room space while another user wishes to watch television.

c. Example Control Devices

FIG. 3 shows a functional block diagram of an example control device 300that may be configured to be one or both of the control devices 126 and128 of the media playback system 100. As shown, the control device 300may include a processor 302, memory 304, a network interface 306, and auser interface 308. In one example, the control device 300 may be adedicated controller for the media playback system 100. In anotherexample, the control device 300 may be a network device on which mediaplayback system controller application software may be installed, suchas for example, an iPhone™ iPad™ or any other smart phone, tablet ornetwork device (e.g., a networked computer such as a PC or Mac™).

The processor 302 may be configured to perform functions relevant tofacilitating user access, control, and configuration of the mediaplayback system 100. The memory 304 may be configured to storeinstructions executable by the processor 302 to perform those functions.The memory 304 may also be configured to store the media playback systemcontroller application software and other data associated with the mediaplayback system 100 and the user.

The microphone(s) 310 may include an audio sensor configured to convertdetected sounds into electrical signals. The electrical signal may beprocessed by the processor 302. In one case, if the control device 300is a device that may also be used as a means for voice communication orvoice recording, one or more of the microphone(s) 310 may be amicrophone for facilitating those functions. For instance, the one ormore of the microphone(s) 310 may be configured to detect sound within afrequency range that a human is capable of producing and/or a frequencyrange audible to humans. Other examples are also possible.

In one example, the network interface 306 may be based on an industrystandard (e.g., infrared, radio, wired standards including IEEE 802.3,wireless standards including IEEE 802.11a, 802.11b, 802.11g, 802.11n,802.11ac, 802.15, 4G mobile communication standard, and so on). Thenetwork interface 306 may provide a means for the control device 300 tocommunicate with other devices in the media playback system 100. In oneexample, data and information (e.g., such as a state variable) may becommunicated between control device 300 and other devices via thenetwork interface 306. For instance, playback zone and zone groupconfigurations in the media playback system 100 may be received by thecontrol device 300 from a playback device or another network device, ortransmitted by the control device 300 to another playback device ornetwork device via the network interface 306. In some cases, the othernetwork device may be another control device.

Playback device control commands such as volume control and audioplayback control may also be communicated from the control device 300 toa playback device via the network interface 306. As suggested above,changes to configurations of the media playback system 100 may also beperformed by a user using the control device 300. The configurationchanges may include adding/removing one or more playback devices to/froma zone, adding/removing one or more zones to/from a zone group, forminga bonded or consolidated player, separating one or more playback devicesfrom a bonded or consolidated player, among others. Accordingly, thecontrol device 300 may sometimes be referred to as a controller, whetherthe control device 300 is a dedicated controller or a network device onwhich media playback system controller application software isinstalled.

The user interface 308 of the control device 300 may be configured tofacilitate user access and control of the media playback system 100, byproviding a controller interface such as the controller interface 400shown in FIG. 4. The controller interface 400 includes a playbackcontrol region 410, a playback zone region 420, a playback status region430, a playback queue region 440, and an audio content sources region450. The user interface 400 as shown is just one example of a userinterface that may be provided on a network device such as the controldevice 300 of FIG. 3 (and/or the control devices 126 and 128 of FIG. 1)and accessed by users to control a media playback system such as themedia playback system 100. Other user interfaces of varying formats,styles, and interactive sequences may alternatively be implemented onone or more network devices to provide comparable control access to amedia playback system.

The playback control region 410 may include selectable (e.g., by way oftouch or by using a cursor) icons to cause playback devices in aselected playback zone or zone group to play or pause, fast forward,rewind, skip to next, skip to previous, enter/exit shuffle mode,enter/exit repeat mode, enter/exit cross fade mode. The playback controlregion 410 may also include selectable icons to modify equalizationsettings, and playback volume, among other possibilities.

The playback zone region 420 may include representations of playbackzones within the media playback system 100. In some embodiments, thegraphical representations of playback zones may be selectable to bringup additional selectable icons to manage or configure the playback zonesin the media playback system, such as a creation of bonded zones,creation of zone groups, separation of zone groups, and renaming of zonegroups, among other possibilities.

For example, as shown, a “group” icon may be provided within each of thegraphical representations of playback zones. The “group” icon providedwithin a graphical representation of a particular zone may be selectableto bring up options to select one or more other zones in the mediaplayback system to be grouped with the particular zone. Once grouped,playback devices in the zones that have been grouped with the particularzone will be configured to play audio content in synchrony with theplayback device(s) in the particular zone. Analogously, a “group” iconmay be provided within a graphical representation of a zone group. Inthis case, the “group” icon may be selectable to bring up options todeselect one or more zones in the zone group to be removed from the zonegroup. Other interactions and implementations for grouping andungrouping zones via a user interface such as the user interface 400 arealso possible. The representations of playback zones in the playbackzone region 420 may be dynamically updated as playback zone or zonegroup configurations are modified.

The playback status region 430 may include graphical representations ofaudio content that is presently being played, previously played, orscheduled to play next in the selected playback zone or zone group. Theselected playback zone or zone group may be visually distinguished onthe user interface, such as within the playback zone region 420 and/orthe playback status region 430. The graphical representations mayinclude track title, artist name, album name, album year, track length,and other relevant information that may be useful for the user to knowwhen controlling the media playback system via the user interface 400.

The playback queue region 440 may include graphical representations ofaudio content in a playback queue associated with the selected playbackzone or zone group. In some embodiments, each playback zone or zonegroup may be associated with a playback queue containing informationcorresponding to zero or more audio items for playback by the playbackzone or zone group. For instance, each audio item in the playback queuemay comprise a uniform resource identifier (URI), a uniform resourcelocator (URL) or some other identifier that may be used by a playbackdevice in the playback zone or zone group to find and/or retrieve theaudio item from a local audio content source or a networked audiocontent source, possibly for playback by the playback device.

In one example, a playlist may be added to a playback queue, in whichcase information corresponding to each audio item in the playlist may beadded to the playback queue. In another example, audio items in aplayback queue may be saved as a playlist. In a further example, aplayback queue may be empty, or populated but “not in use” when theplayback zone or zone group is playing continuously streaming audiocontent, such as Internet radio that may continue to play untilotherwise stopped, rather than discrete audio items that have playbackdurations. In an alternative embodiment, a playback queue can includeInternet radio and/or other streaming audio content items and be “inuse” when the playback zone or zone group is playing those items. Otherexamples are also possible.

When playback zones or zone groups are “grouped” or “ungrouped,”playback queues associated with the affected playback zones or zonegroups may be cleared or re-associated. For example, if a first playbackzone including a first playback queue is grouped with a second playbackzone including a second playback queue, the established zone group mayhave an associated playback queue that is initially empty, that containsaudio items from the first playback queue (such as if the secondplayback zone was added to the first playback zone), that contains audioitems from the second playback queue (such as if the first playback zonewas added to the second playback zone), or a combination of audio itemsfrom both the first and second playback queues. Subsequently, if theestablished zone group is ungrouped, the resulting first playback zonemay be re-associated with the previous first playback queue, or beassociated with a new playback queue that is empty or contains audioitems from the playback queue associated with the established zone groupbefore the established zone group was ungrouped. Similarly, theresulting second playback zone may be re-associated with the previoussecond playback queue, or be associated with a new playback queue thatis empty, or contains audio items from the playback queue associatedwith the established zone group before the established zone group wasungrouped. Other examples are also possible.

Referring back to the user interface 400 of FIG. 4, the graphicalrepresentations of audio content in the playback queue region 440 mayinclude track titles, artist names, track lengths, and other relevantinformation associated with the audio content in the playback queue. Inone example, graphical representations of audio content may beselectable to bring up additional selectable icons to manage and/ormanipulate the playback queue and/or audio content represented in theplayback queue. For instance, a represented audio content may be removedfrom the playback queue, moved to a different position within theplayback queue, or selected to be played immediately, or after anycurrently playing audio content, among other possibilities. A playbackqueue associated with a playback zone or zone group may be stored in amemory on one or more playback devices in the playback zone or zonegroup, on a playback device that is not in the playback zone or zonegroup, and/or some other designated device.

The audio content sources region 450 may include graphicalrepresentations of selectable audio content sources from which audiocontent may be retrieved and played by the selected playback zone orzone group. Discussions pertaining to audio content sources may be foundin the following section.

d. Example Audio Content Sources

As indicated previously, one or more playback devices in a zone or zonegroup may be configured to retrieve for playback audio content (e.g.according to a corresponding URI or URL for the audio content) from avariety of available audio content sources. In one example, audiocontent may be retrieved by a playback device directly from acorresponding audio content source (e.g., a line-in connection). Inanother example, audio content may be provided to a playback device overa network via one or more other playback devices or network devices.

Example audio content sources may include a memory of one or moreplayback devices in a media playback system such as the media playbacksystem 100 of FIG. 1, local music libraries on one or more networkdevices (such as a control device, a network-enabled personal computer,or a networked-attached storage (NAS), for example), streaming audioservices providing audio content via the Internet (e.g., the cloud), oraudio sources connected to the media playback system via a line-in inputconnection on a playback device or network devise, among otherpossibilities.

In some embodiments, audio content sources may be regularly added orremoved from a media playback system such as the media playback system100 of FIG. 1. In one example, an indexing of audio items may beperformed whenever one or more audio content sources are added, removedor updated. Indexing of audio items may involve scanning foridentifiable audio items in all folders/directory shared over a networkaccessible by playback devices in the media playback system, andgenerating or updating an audio content database containing metadata(e.g., title, artist, album, track length, among others) and otherassociated information, such as a URI or URL for each identifiable audioitem found. Other examples for managing and maintaining audio contentsources may also be possible.

The above discussions relating to playback devices, controller devices,playback zone configurations, and media content sources provide onlysome examples of operating environments within which functions andmethods described below may be implemented. Other operating environmentsand configurations of media playback systems, playback devices, andnetwork devices not explicitly described herein may also be applicableand suitable for implementation of the functions and methods.

III. Example Methods and Systems Related to Manipulation of PlaybackDevice Response Using an Acoustic Filter

As discussed above, some examples described herein include, among otherthings, an acoustic filter that is configured to be included as acomponent of a playback device. In operation, the acoustic filter mayreceive sound waves of a first frequency (or range of frequencies)emitted from an audio driver of the playback device and reshape theradiation pattern of the sound waves of the first frequency to be lessdirected along an axis of the audio driver. The acoustic filter may alsoreceive sound waves of a second frequency (or range of frequencies)emitted from the audio driver and pass the sound waves of the secondfrequency without substantial alteration. Other aspects of the exampleswill be made apparent in the remainder of the description herein.

Hereinafter, any reference to a “first frequency” may also refer to afirst range of frequencies that includes the first frequency, and anyreference to a “second frequency” may also refer to a second range offrequencies that includes the second frequency.

FIG. 5 shows an example playback device 500 including an acoustic filter510. In some examples, the acoustic filter 510 may resemble acousticfilter 610 depicted in FIG. 6 or acoustic filter 710 depicted in FIGS.7B, 7C, and 7D. As such, the acoustic filter 510 may be composed ofmetal, plastic, carbon fiber, or similar materials, have a somewhatrectangular shape, and have one or more holes. The acoustic filter 510may have a shape other than a rectangle as well. In some instances, theholes of the acoustic filter 510 may be spaced with some degree ofrandom and/or non-random variance.

The playback device 500 may include several audio drivers, namelywoofers 511A, 511B, and 511C, and tweeters 513A, 513B, and 513C. Theacoustic filter 510 may be positioned in front of the tweeter 513B sothat the acoustic filter 510 may receive at least some of the soundwaves emitted by the tweeter 513B. As shown in FIG. 5, the acousticfilter 510 may be sized and positioned so that (i) some of the soundwaves emitted by the tweeter 513B bypass the acoustic filter 510 and(ii) substantially all of the sound waves emitted by the audio drivers511A, 511B, 511C, 513A, and 513C bypass the acoustic filter 510.

Additional examples of the acoustic filter 510 are included in U.S.Non-Provisional patent application Ser. No. 14/831,910, filed on Aug.21, 2015, the entirety of which is incorporated by reference in itsentirety.

FIGS. 7A, 7B, 7C, and 7D depict example radiation patterns of an audiodriver 702. The radiation patterns depicted in FIGS. 7A-D might not beshown to scale and may differ somewhat in shape from the actual shapesthe depicted radiation patterns take during operation of the audiodriver 702. In some examples, the audio driver 702 in FIGS. 7A-Drepresents the tweeter 513B depicted in FIG. 5.

FIG. 7A shows example radiation patterns of the audio driver 702. Theaudio driver 702 may generate sound waves of a first frequency (e.g.,12-16 kHz) that radiate according to a first radiation pattern 704. Theaudio driver 702 may also generate sound waves of a second frequency(e.g., 6-10 kHz) that radiate according to a second radiation pattern706. As shown in FIG. 7A, the first radiation pattern 704 has a maximummagnitude 707 along an axis 708 of the audio driver 702, whereas thesecond radiation pattern 706 is substantially omnidirectional. In otherexamples, the second radiation pattern 706 might not be substantiallyomnidirectional, but may still be less directed along the axis 708 thanthe first radiation pattern 704. In some examples, the axis 708 maycorrespond to a center line or axis of symmetry of the audio driver 702and/or a center line or axis of symmetry of a playback device thatincludes the audio driver 702, but the axis 708 may take on other formsas well. For example, the axis 708 may represent a rotational axis ofsymmetry of the tweeter 513B of FIG. 5.

FIG. 7B shows an example acoustic filter 710 and further exampleradiation patterns of the audio driver 702. In some examples, theacoustic filter 710 may represent the acoustic filter 510 of FIG. 5. Theacoustic filter 710 may include holes that are configured to attenuatesound waves of the first frequency. In some instances, the acousticfilter 710 is placed in front of the audio driver 702 to produce aneffective radiation pattern 712 for sound waves of the first frequencythat are emitted by the audio driver 702.

In operation, the acoustic filter 710 receives a first set of soundwaves generated by the audio driver 702. The first set of sound wavesoscillate at the first frequency and propagate within the first range ofdirections 722. The first range of directions 722 (i) may correspond todirections from which the acoustic filter 710 is positioned to receivesound waves propagating from the audio driver 702 and (ii) may includethe axis 708. The first set of sound waves may be attenuated by theacoustic filter 710, resulting in the effective radiation pattern 712that is less directed along the axis 708 than the first radiationpattern 704. For example, the effective radiation pattern 712 may have amaximum magnitude 709 along the axis 708 like the maximum magnitude 707of the first radiation pattern 704. However, the maximum magnitude 709of the effective radiation pattern 712 may be less than the maximummagnitude 707 of the first radiation pattern 704.

The audio driver 702 also generates a second set of sound waves of thefirst frequency that propagate within the second range of directions724. The second range of directions 724 may correspond to directionsfrom which the acoustic filter 710 is not positioned to receive soundwaves propagating from the audio driver 702 and might not include theaxis 708. As such, the second set of sound waves propagating within thesecond range of directions 724 may bypass the acoustic filter 710without being substantially attenuated by the holes of the acousticfilter 710. As a result, the first radiation pattern 704 and theeffective radiation pattern 712 may be substantially equal throughoutthe second range of directions 724.

Sound waves of the second frequency generated by the audio driver 702,whether propagating within the first range of directions 722 or thesecond range of directions 724, might not be substantially attenuated bythe acoustic filter 710. That is, sound waves of the second frequencypropagating within the first range of directions 722 may pass throughthe holes of the acoustic filter without being substantially attenuatedand sound waves of the second frequency propagating within the secondrange of directions 724 might not interact with the acoustic filter 710at all.

FIG. 7C shows yet further example radiation patterns of the audio driver702. In some instances, it may be useful to further manipulate theeffective radiation pattern 712 so that listeners at a variety oflocations may perceive a loudness of the first frequency relative to thesecond frequency that closely resembles the source audio content. Theplayback device that includes the audio driver 702 may provide a signalto the audio driver 702 so that the audio driver 702 generates soundwaves according to the amplitudes and respective audio frequenciesrepresented by the signal. The playback device may amplify a portion ofthe signal that corresponds to the sound waves of the first frequency tocompensate for the attenuation of the sound waves of the first frequencythat the acoustic filter 710 provides.

For example, the effective radiation pattern 712 has a reduced maximummagnitude 709 when compared to the maximum magnitude 707 of the secondradiation pattern 706. (The first radiation pattern 704 and the secondradiation pattern 706 may share a maximum magnitude 707.) By amplifyingthe portion of the signal that corresponds to the first frequency, aneffective radiation pattern 714 may be formed. In a sense, this occursby “expansion” of the effective radiation pattern 712.

The effective radiation pattern 714 may be substantially equal inmagnitude to the second radiation pattern 706 over the first range ofdirections 722. In FIG. 7C, the effective radiation pattern 714 is shownas being about equal in magnitude to the second radiation pattern 706over most of the first range of directions 722. Near the boundaries 723and 725 that separate the first range of directions 722 from the secondrange of directions 724, a difference in magnitude between the effectiveradiation pattern 714 and the second radiation pattern 706 becomes morepronounced, but may still be considered non-substantial.

FIG. 7D shows yet further example radiation patterns of the audio driver702. Here, the playback device may amplify the portion of the signalcorresponding to the first frequency even more when compared to theexample depicted in FIG. 7C. This increased amplification may result inthe effective radiation pattern 716 for sound waves of the firstfrequency generated by the audio driver 702. The effective radiationpattern 716 may be substantially equal in magnitude to the secondradiation pattern 706 over the first range of directions 722. In FIG.7D, the effective radiation pattern 716 is shown as being about equal inmagnitude to the second radiation pattern 706 over a portion of thefirst range of directions 722 near the axis 708. At directions betweenthe axis 708 and respective boundaries 723 and 725, a difference inmagnitude between the effective radiation pattern 716 and the secondradiation pattern 706 becomes more pronounced, but may still beconsidered non-substantial. Near the respective boundaries 723 and 725that separate the first range of directions 722 from the second range ofdirections 724, the magnitudes of the second radiation pattern 706 andthe effective radiation pattern 716 are about equal.

FIG. 6 shows an example acoustic filter 610. The acoustic filter 610 maybe similar to the acoustic filter 510 depicted in FIG. 5 or the acousticfilter 710 depicted in FIGS. 7B-D, for example. The acoustic filter 610includes holes that are perhaps spaced according to a pattern. In otherexamples, the holes may be spaced randomly.

The acoustic filter 610 may include several rows of holes 612 andseveral rows of holes 614. Although FIG. 6 depicts four rows of holes612 and four rows of holes 614, the acoustic filter 610 may include moreor less rows of holes. The rows 612 and 614 may be separated byrespective distances 602 along a first axis. The holes of the rows 612and 614 may be separated by respective distances 604 along a secondaxis. In other examples, the holes may be spaced randomly, irregularly,or with varying patterns.

In some examples, the distance 602 may be about 0.7 mm or any distancegreater than 0.55 mm and less than 0.75 mm. Similarly, the distance 604may be about 0.61 mm or any distance greater than 0.55 mm and less than0.75 mm. The distances 602 and 604 may take on other values as well.

The holes 601 of the acoustic filter 610 may have a diameter 603 ofabout 0.35 mm, or any value greater than 0.3 mm and less than 0.4 mm.Other example diameters 603 for the holes 601 are possible as well. Theholes 601 need not all have the same diameter 603.

In some examples, the holes 601 may have a depth (into the page asviewed in FIG. 6) of about 2.0 mm, or any value greater than 1.8 mm andless than 2.2 mm. Other example depths for the holes 601 are possible aswell. The holes 601 need not all have the same depths as the dimensionsof the acoustic filter 610 may differ at various locations.

When the acoustic filter 610 is placed in front of an audio driver, oneor more of the holes 601 may receive sound waves emitted by the audiodriver. The holes 601 may provide frequency-dependent attenuation of thereceived sound waves according to the following equations:

$\begin{matrix}{{H(\omega)} = \sqrt{\frac{1}{{\omega^{4}M_{in}^{2}C_{in}^{2}} + {\omega^{2}R_{in}^{2}C_{in}^{2}} - {2\omega^{2}M_{in}C_{in}} + 1}}} & \lbrack 1\rbrack \\{R_{in} = \frac{\eta\; l}{{\pi\left( {2r} \right)}^{4}}} & \lbrack 2\rbrack \\{M_{in} = {\rho\; l\text{/}\left( {\pi\; r^{2}} \right)}} & \lbrack 3\rbrack \\{C_{in} = {\pi\; r^{2}l\text{/}\left( {\gamma\; P_{a}} \right)}} & \lbrack 4\rbrack\end{matrix}$where ‘η’ is the viscosity of ambient air (e.g., η=0.00018dyne-second/cm²), ‘l’ is the depth of the hole (e.g., l=2.0 mm), ‘r’ isthe radius of the hole (e.g., r=0.175 mm), ‘ρ’ is the density of ambientair (e.g., p=1.225 kg/m³), ‘65’ is the adiabatic factor of ambient air(e.g., γ=1.4), and P_(a) is ambient air pressure (e.g., P_(a)=760 Torr).H(ω) is a mathematical model of a frequency-dependent transfer functionof each hole 601. The actual frequency-dependent attenuation provided bythe holes 601 may vary from equation [1] somewhat due to factors thatare unaccounted for by the model of equation [1]. For example, thefrequency-dependent attenuation characterized by equation [1] may beprimarily based on absorption of sound waves by air within the holes601, however attenuation may occur via other mechanisms such asreflection and diffraction as well.

FIG. 8A shows experimental data representing a measured radiationpattern 802 exhibited by a playback device. The radiation pattern 802represents the response of the playback device at f=16 kHz. The playbackdevice was not equipped with an acoustic filter in the example depictedin FIG. 8A. As shown in FIG. 8A, the radiation pattern 802 has a maximummagnitude of 0 dB at 807 along an axis 808 of the playback device.

FIG. 8B shows experimental data representing a measured radiationpattern 812 exhibited by a playback device. The radiation pattern 812represents the response of the playback device at f=16 kHz. The playbackdevice was equipped with an acoustic filter such as acoustic filter 510or 710 in the example depicted in FIG. 8B. As shown in FIG. 8B, theradiation pattern 812 has a maximum magnitude at 809 along the axis 808of the playback device. The radiation pattern 802 depicted in FIG. 8Aand the radiation pattern 812 depicted in FIG. 8B have both beennormalized so that their respective maximum magnitudes are depicted as 0dB. However, the maximum magnitude 809 of radiation pattern 812 mayactually be less than the maximum magnitude 807 of radiation pattern802, due to the attenuation of sound waves at f=16 kHz provided by theacoustic filter.

The “re-shaping” effect of the acoustic filter can be demonstrated bycomparing the radiation pattern 802 of FIG. 8A with the radiationpattern 812 of FIG. 8B. As shown, the radiation pattern 812 has larger(normalized) magnitudes than the radiation pattern 802 at angles rangingfrom at least about 30°-90° and at least about (−)30°-(−)90°. Accountingfor the normalization of the radiation patterns 802 and 812, this showsthat the acoustic filter was effective in attenuating sound wavesgenerated by the audio driver at least within the directions representedby 30°-(−30°).

IV. Conclusion

The description above discloses, among other things, various examplesystems, methods, apparatus, and articles of manufacture including,among other components, firmware and/or software executed on hardware.It is understood that such examples are merely illustrative and shouldnot be considered as limiting. For example, it is contemplated that anyor all of the firmware, hardware, and/or software aspects or componentscan be embodied exclusively in hardware, exclusively in software,exclusively in firmware, or in any combination of hardware, software,and/or firmware. Accordingly, the examples provided are not the onlyway(s) to implement such systems, methods, apparatus, and/or articles ofmanufacture.

Additionally, references herein to “embodiment” means that a particularfeature, structure, or characteristic described in connection with theembodiment can be included in at least one example embodiment of aninvention. The appearances of this phrase in various places in thespecification are not necessarily all referring to the same embodiment,nor are separate or alternative embodiments mutually exclusive of otherembodiments. As such, the embodiments described herein, explicitly andimplicitly understood by one skilled in the art, can be combined withother embodiments.

The specification is presented largely in terms of illustrativeenvironments, systems, procedures, steps, logic blocks, processing, andother symbolic representations that directly or indirectly resemble theoperations of data processing devices coupled to networks. These processdescriptions and representations are typically used by those skilled inthe art to most effectively convey the substance of their work to othersskilled in the art. Numerous specific details are set forth to provide athorough understanding of the present disclosure. However, it isunderstood to those skilled in the art that certain embodiments of thepresent disclosure can be practiced without certain, specific details.In other instances, well known methods, procedures, components, andcircuitry have not been described in detail to avoid unnecessarilyobscuring aspects of the embodiments. Accordingly, the scope of thepresent disclosure is defined by the appended claims rather than theforgoing description of embodiments.

When any of the appended claims are read to cover a purely softwareand/or firmware implementation, at least one of the elements in at leastone example is hereby expressly defined to include a tangible,non-transitory medium such as a memory, DVD, CD, Blu-ray, and so on,storing the software and/or firmware.

We claim:
 1. An acoustic filter comprising: a surface configured to beat least partially axially aligned with a transducer of a playbackdevice; and an array of apertures in the surface, wherein the array ofapertures is configured to: receive (i) first sound waves of a firstrange of frequencies that radiate according to a first radiation patternhaving a first shape, and (ii) second sound waves of a second range offrequencies that radiate according to a second radiation pattern,wherein at least a portion of the second range of frequencies isdifferent than the first range of frequencies; attenuate the first soundwaves such that the attenuated first sound waves radiate according to athird radiation pattern having a shape different than the first shape;and pass the second sound waves in substantial accordance with thesecond radiation pattern.
 2. The acoustic filter of claim 1 wherein thesecond radiation pattern has a shape different than the first shape. 3.The acoustic filter of claim 1 wherein the first range of frequencieshas a first center frequency, wherein the second range of frequencieshas a second center frequency, and wherein the first center frequency isgreater than the second center frequency.
 4. The acoustic filter ofclaim 1, wherein the first sound waves comprise sound waves generated bythe transducer that include a first set of sound waves that propagatewithin a first range of directions with respect to the acoustic filter,wherein the transducer is configured to generate a second set of soundwaves that propagate within a second range of directions with respect tothe acoustic filter that is outside the first range of directions, andwherein the array of apertures is configured to allow the second set ofsound waves to pass substantially unattenuated through holes defined bythe apertures.
 5. The acoustic filter of claim 4, wherein when theacoustic filter is further configured to attenuate the first set ofsound waves such that the third radiation pattern is substantially equalin magnitude to the second radiation pattern over a third range ofdirections with respect to the acoustic filter.
 6. The acoustic filterof claim 5, wherein the third range of directions includes the firstrange of directions.
 7. The acoustic filter of claim 1, wherein thefirst range of frequencies comprises frequencies within a range of 12-16kilohertz (kHz) and the second range of frequencies comprisesfrequencies within a range of 6-10 kHz.
 8. The acoustic filter of claim1, wherein holes defined by the apertures are sized to absorb the firstsound waves of one or more frequencies in the first range offrequencies.
 9. The acoustic filter of claim 1, wherein the array ofapertures includes a first aperture and a second aperture defining afirst hole and a second hole, respectively, and wherein a center of thefirst hole is separated by a center of the second hole by a distancegreater than or equal to 0.55 millimeter (mm) and less than or equal to0.75 mm.
 10. The acoustic filter of claim 1, wherein the surface has athickness that is greater than or equal than 1.8 mm and less than orequal to 2.2 mm.
 11. A playback device comprising: a transducerconfigured to generate (i) first sound waves comprising a first range offrequencies that radiate according to a first radiation pattern having afirst shape and (ii) second sound waves comprising a second range offrequencies that radiate according to a second radiation pattern; and anacoustic filter axially aligned with at least a portion of thetransducer, wherein the acoustic filter comprises an array of apertures,and wherein the acoustic filter is configured to: attenuate the firstsound waves such that the attenuated first sound waves radiate accordingto a third radiation pattern having a shape different than the firstshape; and pass the second sound waves in substantial accordance withthe second radiation pattern.
 12. The acoustic filter of claim 11wherein the second radiation pattern has a different shape than thefirst radiation pattern.
 13. The acoustic filter of claim 11 wherein thefirst range of frequencies has a first center frequency, wherein thesecond range of frequencies has a second center frequency, and whereinthe first center frequency is greater than the second center frequency.14. The playback device of claim 11, wherein the first sound wavesinclude a first set of first sound waves that propagate within a firstrange of directions with respect to the transducer, wherein thetransducer is further configured to generate a second set of first soundwaves that propagate within a second range of directions with respect tothe transducer, the second range of directions being different from thefirst range of directions, and wherein the acoustic filter is configuredto allow the second set of first sound waves to pass substantiallyunattenuated through the apertures.
 15. The playback device of claim 14,wherein the acoustic filter is further configured to attenuate the firstset of first sound waves such that the third radiation pattern issubstantially equal in magnitude to the second radiation pattern over athird range of directions with respect to the transducer.
 16. Theplayback device of claim 15, wherein the third range of directionsincludes the first range of directions.
 17. The playback device of claim11, wherein the first range of frequencies includes one or morefrequencies within a range of 12-16 kilohertz (kHz), and wherein thesecond range of frequencies includes one or more frequencies within arange of 6-10 kHz.
 18. The playback device of claim 11, wherein thearray of apertures includes a first aperture and a second aperturedefining a first hole and a second hole, respectively, and wherein acenter of the first hole is separated by a center of the second hole bya distance greater than or equal to 0.55 mm and less than or equal to0.75 mm.
 19. The playback device of claim 11, wherein at least one ofthe apertures has a diameter that is greater than 0.3 mm and less than0.4 mm.
 20. A playback device comprising: a transducer configured togenerate (i) first sound waves comprising a first range of frequenciesthat radiate according to a first radiation pattern having a first shapeand (ii) second sound waves comprising a second range of frequenciesthat radiate according to a second radiation pattern; and an acousticfilter axially aligned with at least a portion of the transducer,wherein the acoustic filter comprises an array of apertures, and whereinthe acoustic filter is configured to: reshape the first radiationpattern such that the first sound waves radiate according to a thirdradiation pattern having a shape different than the first shape; andpass the second sound waves in substantial accordance with the secondradiation pattern.